// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef LIB_FIDL_CPP_MESSAGE_BUFFER_H_
#define LIB_FIDL_CPP_MESSAGE_BUFFER_H_

#include <stdint.h>

#include <lib/fidl/cpp/builder.h>
#include <lib/fidl/cpp/message.h>
#include <zircon/fidl.h>
#include <zircon/types.h>

namespace fidl {

class MessageBuffer {
public:
    // Creates a |MessageBuffer| that allocates buffers for message of the
    // given capacities.
    //
    // The buffers are freed when the |MessageBuffer| is destructed.
    explicit MessageBuffer(
        uint32_t bytes_capacity = ZX_CHANNEL_MAX_MSG_BYTES,
        uint32_t handles_capacity = ZX_CHANNEL_MAX_MSG_HANDLES);

    // The memory that backs the message is freed by this destructor.
    ~MessageBuffer();

    // The memory in which bytes can be stored in this buffer.
    uint8_t* bytes() const { return buffer_; }

    // The total number of bytes that can be stored in this buffer.
    uint32_t bytes_capacity() const { return bytes_capacity_; }

    // The memory in which handles can be stored in this buffer.
    zx_handle_t* handles() const;

    // The total number of handles that can be stored in this buffer.
    uint32_t handles_capacity() const { return handles_capacity_; }

    // Creates a |Message| that is backed by the memory in this buffer.
    //
    // The returned |Message| contains no bytes or handles.
    Message CreateEmptyMessage();

    // Creates a |Builder| that is backed by the memory in this buffer.
    Builder CreateBuilder();

private:
    uint8_t* const buffer_;
    const uint32_t bytes_capacity_;
    const uint32_t handles_capacity_;
};

} // namespace fidl

#endif // LIB_FIDL_CPP_MESSAGE_BUFFER_H_